Remove redundant if object javascript

Hello I have an object that I want to browse and when a value is equal to true I fill an array.
My code works but I don’t think it’s good to put so much if.

daysOfWeek: {
      lundi: true,
      mardi: true,
      mercredi: true,
      jeudi: false,
      vendredi: true,
      samedi: true,
      dimanche: true
    }

 let days = []

    if (daysOfWeek != null) {
        if (daysOfWeek.lundi === true) {
            days.push(2)
        }
        if (daysOfWeek.mardi === true) {
            days.push(3)
        }
        if (daysOfWeek.mercredi === true) {
            days.push(4)
        }
        if (daysOfWeek.jeudi === true) {
            days.push(5)
        }
        if (daysOfWeek.vendredi === true) {
            days.push(6)
        }
        if (daysOfWeek.samedi === true) {
            days.push(7)
        }
        if (daysOfWeek.dimanche === true) {
            days.push(1)
        }
    }
    return days 

days = [2,3,4,6,7,1]

I tried the switch/case but it doesn’t work for conditions.

Does anyone have another solution for me to explore?

>Solution :

1. I suggest you order and number the days Sunday:0 and Saturday:6 to match JavaScript’s order and numbering. Otherwise add one to the index as I do below.
   Note that your example output did not match the object values

2. Use reduce:

const daysOfWeek =  {
  dimanche: true,
  lundi: true,
  mardi: true,
  mercredi: true,
  jeudi: false,
  vendredi: true,
  samedi: true
}

// curr is the true/false. I use && to shortcut and the comma operator to return the accumulator
const days = Object.values(daysOfWeek)
  .reduce((acc, curr, index) => (curr && acc.push(index + 1), acc), []);
  
  console.log(days)